The present invention relates to an injection device for use with intravenous administration sets. More particularly, the present invention concerns itself with an anti backflow injection device which is particularly useful for the repeated administration of intravenous drugs during surgical procedures.
In the course of the typical surgical procedure, the anesthetist delivers multiple doses of one or more intravenous anesthetics from one or more syringes, usually through the means of an IV administration set associated with the patient undergoing surgery. In this regard, the injection site of the administration set is taped to an IV pole or to the operating table itself, and when the anesthetist is ready to deliver a dose of an intravenous anesthetic drug, the needle of a syringe filled with the drug is made to puncture the rubber diaphragm of the injection port. The appropriate amount of drug is then injected directly into the flowing parenteral solution and is thereby infused into the circulatory system of the patient. The needle of the syringe is then removed, and the syringe is put aside. Then, when another dose of the same intravenous anesthetic or a dose of another drug is in order, the anesthetist repeats the above-described procedure.
One significant drawback of this procedure is the difficulty experienced by the anesthetist when attempting, with one hand, to pierce the diaphragm of the injection port with the needle of the syringe containing the intravenous drug. This seemingly simple operation is in fact quite difficult during surgery. There is no guide for directing the needle into the diaphragm. In addition, the needle cannot be left in the injection site because then there will be a certain amount of backflow of intravenous fluid into the syringe, due to the pressure head exerted by the supply of parenteral solution. This backflow dilutes the drug and renders assessment of infused drug dose very difficult. Occasionally, there is enough backflow to push the syringe plunger entirely out of the barrel of the syringe, and thus spill the drug on the floor. Accordingly, the syringe is generally removed at the end of each injection. And this, of course, increases the risk of contamination, both of the syringe needle and the contents of the syringe.
It is toward the elimination of the foregoing disadvantages, and the provision of an improved IV injection device, that the present invention is directed.